All Free Biology MCQs with Answers

3581. In photosynthesis dark reaction, is called so because:

• A. It occurs in dark
• B. It does not require light energy
• C. It cannot occur during daytime
• D. It occurs more rapidly at night

Explanation: "The explanation for this question will be added soon!".

3582. Photosystem 2 absorbs maximum wavelenght of light?

• A. 750
• B. 650
• C. 680
• D. 670

Explanation: The chlorophyll, a special pair of the two photosystems, absorb different wavelengths of light. The PSII special pair absorbs best at 680 nm, while the PSI special absorbs best at 700 nm.

3583. Cancer cells require large amounts of ATP, which of the following produce a higher number of ATP?

• A. Electron transport chain
• B. Oxidative phosphorylation
• C. Krebs Cycle
• D. Glycolysis

Explanation: Cancer cells require large amounts of energy in the form of ATP. Which of the following processes results in the greatest production of ATP? Explanation: Oxidative phosphorylation in the mitochondria is the major contributor to the total ATP pool in most eukaryotic cells.

3584. Phosphofructokinase enzyme converts fructose-6-phosphate into _.

• A. Fructose-I ,4-phosphate
• B. Fructose-1,6-bisphosphate
• C. Bisphosphate
• D. Fructose

Explanation: The enzyme phosphofructokinase transforms fructose-6-phosphate to fructose-1,6-diphosphate.

3585. The G3P is an end product of this process:

• A. Kreb's cycle
• B. Calvin cycle
• C. Chemiosmosis
• D. Electron transport chain

Explanation: Calvin cycle (also known as the Calvin-Benson cycle or the C3 cycle) is a series of reactions that occur in the chloroplasts of plants during photosynthesis. It is a light-independent process that uses the products of the light-dependent reactions (ATP and NADPH) to convert carbon dioxide (CO2) into glyceraldehyde 3-phosphate (G3P).

3586. The number of ATP produced when a molecule of glucose undergoes fermentation is?

• A. 4
• B. 36
• C. 2
• D. 38

Explanation: Anaerobic respiration is a type of respiration that produces energy without using oxygen as the final electron acceptor.In microorganisms, the term anaerobic respiration is replaced by fermentation.Fermentation of glucose occurs in two stages.During the first stage, glucose is converted into pyruvate through the multi-step process of glycolysis and 2 ATP and 2 NADH are generated.In the next stage, the pyruvate that is formed during glycolysis is broken down into lactic acid or ethanol and carbon dioxide. ATP is not produced during this stage, instead the 2 NADH generated during the previous stage are consumed.Thus a total of 2 ATPs are generated from the fermentation of a glucose molecule.

3587. How are high energy phosphate bonds broken down in ATP?

• A. Anabolism
• B. Catabolism
• C. Hydrolysis
• D. All of these

Explanation: Hydrolysis is a chemical process in which a molecule is split into two parts by the addition of a water molecule. The term "hydrolysis" is derived from the Greek words "hydro," meaning water, and "lysis," meaning to break. In hydrolysis reactions, a water molecule is used to break a chemical bond, resulting in the formation of two new molecules.

3588. Cytochrome c is oxidised by which coenzyme in the ETC?

• A. Cytochrome a
• B. Coenzyme Q
• C. Coenzyme B
• D. Coenzyme A

Explanation: Cytochrome c is oxidized by Cytochrome a.OPTION A: Cytochrome a oxidizes cytochrome C.OPTION B: Coenzyme Q is located in the inner mitochondrial membrane where it transports electrons from complexes I and II to complex III to provide energy for proton translocation to the intermembrane space.OPTION C: Co enzyme B facilitates the metabolic processes of all forms of animal life.OPTION D: Coenzyme A has a clearly defined role as a cofactor for a number of oxidative and biosynthetic reactions in intermediary metabolism.

3589. What are the end products of the ETC in animals?

• A. ATP
• B. Carbon dioxide
• C. Water
• D. Both Options A and C are correct

Explanation: OPTION A: The end product of cellular respiration is ATP. OPTION B: CO2 is a gas and has no link with it. OPTION C: Water is a molecule and has nothing to do with it.OPTION D: The end products of the ETC or electron transport chain are the formation of ATP, NAD+, FAD, water, and protons. Hence both A and C are correct.

3590. What is the correct sequence for movement of electrons during the light-dependent reaction?

• A. P680, P700, water, NADP
• B. Water, P700, NADP, P680
• C. P700, P680, NADP, water
• D. Water, P680, P700, NADP

Explanation: In photosynthesis, a light-dependent reaction uses light energy from the sun to split water which has been taken in by the organism. Water, when split, gives oxygen, hydrogen, and electrons. These electrons move through structures in chloroplasts and, by chemiosmosis, make ATP.It is non-cyclic phosphorylation that involves the photolysis of water, releasing electrons that pass through Photosystem II (680), to Photosystem I (700) and are ultimately transferred to NADP forming NADPH.